It is desirable for a satellite radio receiver system to use a single coaxial cable to couple signals from an antenna assembly to a receiver. A single cable is desirable because it minimizes cost. This single cable feature is particularly desired by manufactures of automobiles because the single cable simplifies installation into the automobile. It has been suggested that signal data may be more reliably received if the antenna assembly has multiple antennas. However, if signals from multiple antennas are simply combined at the antenna assembly, there is a risk that a signal on one antenna may be 180 electrical degrees out of phase with another antenna, and so the signals will cancel each other when combined.
It has been suggested that a satellite signal received by one or more of the antennas in a multiple antenna system could be converted or frequency shifted in order to produce an intermediate signal having a different center frequency by equipping the antenna assembly with a mixer driven and a local oscillator. However, if the intermediate signal has a center frequency that is proximate to a terrestrial based broadcast signal, there is a risk of the terrestrial signal overloading an amplifier configured to amplify the relatively weak satellite level signal in the intermediate signal. To reduce the risk of overloading the amplifier, is has been suggested that a band pass filter such as a surface acoustic wave (SAW) filter be used to protect the amplifier input. However, if the pass band of the filter is narrow enough to be effective to protect the amplifier, the local oscillator frequency must be precisely controlled so the intermediate signal is in the middle of the pass band, and the local oscillator frequency may need to be changed if reception of a different satellite signal having a different center frequency is desired.